core

#### Feature Weights

The purpose of weights is to aid in simultaneous evaluation of Position or Profile tolerances.

You can specify feature weights, or you can have PC-DMIS automatically generate feature weights based on the tolerances' values.

Specified Weights

Each feature used as an input has an associated weight. The default value for these weights is 1. You can modify the weights in the Edit window (View | Edit Window) or in the Best Fit Alignment dialog box (Insert | Alignment | New | Best Fit button). The values of these weights affect the resulting alignment. The larger the weight of a particular feature, the more the resulting alignment will attempt to match the measured value of that feature to its theoretical value. This association allows you to assign priorities to the features in the alignment. If the weights of all the input features are equal, then the features will be treated equally regardless of the value of the weight.

You can edit any of the weights by selecting the feature in the Alignment features list and double-clicking the specific weight value. Edit the value as needed and then click outside the field to set the new value. The new value will then be assigned to that feature and used during the calculations.

Weights may also be assigned to each feature based on its associated dimension. If there is no associated dimension, it will be assigned a default tolerance. Assign the weights by clicking the Set button. A composite weight for the feature is then computed by multiplying the user-defined weights with the tolerance weights.

Tolerance-Generated Weights

For tolerance-based weights, a Min_Max fit reduces the percentage of the available tolerance that each feature uses. The Least Squares fit reduces the "average" amount of tolerance that all features use.

Because the generated weights are reciprocals of the tolerances, a feature with a relatively small weight (or lower priority) corresponds to a large tolerance zone. This gives it more freedom to move without affecting the other features. A feature with a relatively large weight (or small tolerance zone) gets a high priority in the alignment process.

Using Weights for Simultaneous Evaluation

1. Create some dimensions with the appropriate tolerances. Choose "no fit" for these dimensions. Do not include these dimensions in the report. These dimensions are for-reference-only. These are only present to inform the best-fit alignment what the tolerances are.

2. Create a best-fit alignment that automatically creates weights on the toleranced features. The best-fit alignment takes into account the tolerance sizes and any applicable bonus as it creates the weights.

3. Create a second set of dimensions with the appropriate tolerances, using the weighted best-fit alignment. Include these dimensions in the report.